Tehran: France's foreign minister visited Iran on Monday on a delicate mission to affirm Europe's support for a nuclear deal that opened Iran's economy while echoing US concern about Tehran's missile programme and role in regional conflicts.

Jean-Yves Le Drian aims to save the 2015 nuclear deal, which US President Donald Trump has threatened to quit unless European allies help "fix" it by forcing Iran to change its behaviour in other areas.

"We're not going to be Donald Trump's envoys or Iran's defence lawyers," said a French diplomatic source. "We have our own concerns and will talk to the different sensibilities of the Iranian system to get our point across."

France says Iran must address concern over its ballistic missile programme or risk new sanctions. Iran's missile programme is not covered by the nuclear deal, and Tehran says it will not bow to pressure to halt it.

"Our missile work is... in line with our defensive policy, which poses no threat to any country," the secretary of Iran's Supreme National Security Council, Ali Shamkhani, told Le Drian, according to the Students News Agency ISNA.

Earlier, the semi-official Tasnim news agency quoted an Iranian armed forces spokesman as saying: "Iran's missile programme will continue non-stop and foreign powers have no right to intervene on this issue."

Hardline media reacted angrily to Le Drian's visit with headlines like "Rude guest" and "Weapons of mass seduction". Fars news agency said a group of hardliners gathered at Tehran's International Mehrabad Airport to protest Le Drian's visit.

The 2015 accord between France, Britain, Germany, Russia, China and the United States gave Iran relief from economic sanctions in return for curbs to its nuclear programme, allowing Tehran to talk trade with Europe for the first time in years.

But so far the deal, pragmatist President Hassan Rouhani's headline achievement, has yet to bring the economic benefits many Iranians yearn for. That has slowed Rouhani's efforts to engage with the West, opposed by allies of Iran's top authority Supreme Leader Ayatollah Ali Khamenei.

France has been quick to restore trade ties. Planemaker Airbus, oil major Total and automobile manufacturers Peugeot and Renault have signed deals, all at risk if Trump walks out of the accord.

In an effort to keep him on board, French President Emmanuel Macron has criticised Iran's missile programme and raised the possibility of new sanctions. On the eve of Le Drian's visit, Macron told Rouhani by phone that France expects Iran to make a "constructive contribution" to solving crises in the region.

France wants Washington to see the nuclear deal separately from Iran's regional activities and missile programme, and Le Drian will stress Macron's commitment to the accord.

Le Drian also met Iranian Foreign Minister Mohammad Javad Zarif.

An official close to Rouhani said Iran "has always been open to talks and to resolve issues through diplomacy... but this does not mean we will yield to unjust pressure over our inevitable rights, whether defensive or anything else."

While France says Iran is sticking to the terms of the nuclear deal, it argues that it may be violating part of the UN resolution enshrining the accord. The resolution calls on Tehran to refrain from work on missiles designed to carry nuclear warheads, although this is not in the accord itself.

"On the ballistics, the Iranian programme is not compatible with (the resolution) and we have a particular concern on the transfer of know-how of ballistic capacity to regional actors," the diplomatic source said.